Semiconductor Patterning Using Self-Aligned Double Patterning
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Solution Overview
Problem
As semiconductor devices continue to shrink, traditional photolithography equipment struggles to achieve the necessary pitch and spacing between elements, approaching the limits of its capabilities, leading to manufacturing challenges with increasing complexity and defect rates.
Innovation Solution
A self-aligned double patterning process is employed, using mandrels, spacers, and an inorganic sacrificial material deposited via CVD, PVD, or ALD to pattern lines at half the minimum pitch achievable by photolithography, allowing for finer pitch semiconductor structures with improved yield and reduced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional photolithography equipment is used to manufacture semiconductor devices, then the manufacturing process is simpler and more established, but the pitch and spacing between elements cannot be reduced below a certain limit
Solution Approach 1:
The patterning process is divided into multiple discrete steps: forming mandrels at a first pitch, depositing spacers on mandrel sidewalls, removing mandrels, and forming sacrificial material. This segmentation allows each step to be optimized independently, achieving sub-photolithographic pitch without requiring a single complex lithography step
Solution Approach 2:
The patent transitions from two-dimensional planar patterning to three-dimensional structures by forming vertical spacers on mandrel sidewalls and using sacrificial material in the spaces between mandrels. This dimensional transition enables pitch multiplication and finer feature spacing that cannot be achieved with traditional planar photolithography
2Manufacturing precision
If photolithography is used to pattern features, then the process is straightforward, but the minimum achievable pitch is limited by equipment capabilities
Solution Approach 1:
Mandrels are formed in advance at a relaxed pitch that is achievable with standard photolithography equipment. These pre-formed mandrels serve as templates for subsequent spacer deposition, allowing the final feature pitch to be smaller than the original mandrel pitch while using conventional lithography tools
Solution Approach 2:
Spacers act as intermediary structures formed on the sidewalls of mandrels. These spacers transfer and refine the pattern from the mandrels to the final feature layer, enabling pitch multiplication and achieving finer feature spacing than the original photolithography process could directly produce
3Quantity of substance
If pitch is reduced to increase device density, then device capacity increases, but manufacturing complexity and defect rates increase
Solution Approach 1:
The spacer structures are self-aligned to the mandrels through conformal deposition, automatically defining precise spacing and position without requiring additional alignment steps. This self-alignment mechanism reduces manufacturing variability and defect rates that would otherwise increase with higher device density
Solution Approach 2:
The patent changes the physical and chemical parameters of the patterning process by using inorganic sacrificial material deposited via CVD, PVD, or ALD instead of traditional organic photoresist. This parameter change improves pattern definition precision and reduces defects, enabling reliable manufacturing at higher device densities
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process enables the manufacturing of semiconductor devices with finer pitch interconnect lines and reduced defects, overcoming the limitations of traditional photolithography by using inorganic materials for improved pattern definition and precision.
Implementation Method 1
The sacrificial material includes an inorganic oxide and is formed using a semiconductor film deposition process
Implementation Method 2
The sacrificial material includes an inorganic oxide and is formed using a semiconductor film deposition process
Implementation Method 3
The sacrificial material includes an inorganic oxide and is formed using a semiconductor film deposition process
Data Source
AI summary
An embodiment method includes defining a first mandrel and a second mandrel over a hard mask layer. The method also includes depositing a spacer layer over and along sidewalls of the first mandrel and the second mandrel, and forming a sacrificial material over the spacer layer between the first mandrel and the second mandrel. The sacrificial material includes an inorganic oxide. The method further includes removing first horizontal portions of the spacer layer to expose the first mandrel and the second mandrel. Remaining portions of the spacer layer provide spacers on sidewalls of the first mandrel and the second mandrel. The method further includes removing the first mandrel and the second mandrel and patterning the hard mask layer using the spacers and the sacrificial material as an etch mask.